Oil products continue to be used as a principal source of energy. Wide-scale production, transport, global use and disposal of petroleum have made them major contaminants in prevalence and quantity in the environment. In accidental spills, actions are taken to remove or remediate or recover the contaminants immediately, especially if they occur in environmentally sensitive areas, for example, in coastal zones. Traditional methods to cope with oil spills are confined to physical containment. Biological methods can have an advantage over the physical-chemical treatment regimes in removing spills in situ as they offer biodegradation of oil fractions by the micro-organisms. Recently, biological methods have been known to play a significant role in bioremediation of oil-polluted coastal areas. Such systems are likely to be of significance in the effective management of sensitive coastal ecosystems chronically subjected to oil spillage. For this reason the aim of this paper is to present an impact of Mn, Cu, Co and Mo quantities on oil biodegradation effectiveness in coastal soil and to determine the relationship between metal concentrations and degradation of two oil products (black oil and diesel fuel). Soil was collected in the Baltic Sea coastal zone oil products degradation area (Klaipeda, Lithuania). The experiment consisted of two parts: study on the influence of micro-elements on the oil product biodegradation process; and analysis of the influence of metal concentration on the number of HDMs. The analysis performed and results obtained address the following areas: impact of metal on a population of hydrocarbon degrading micro-organisms, impact of metals on residual concentrations of oil products, influence of metals on the growth of micro-organisms, inter-relation of metal concentrations with degradation rates. Statistical analysis was made using ;Statgraphics plus' software. The influence of metals on the growth of micro-organisms, the biodegradation process rate and the oil product concentrations were evaluated with analysis of variance. The impact has been investigated separately and synergetically.
Journal of Environmental Engineering and Landscape ManagementPublication details, including instructions for authors and subscription information:Abstract.
Bioremediation is one of the most efficient and widely applied methods of biotechnology, which also plays an important role in cleaning the environment from pollution by oil and oil products as well as rehabilitating the soil. Time is a limiting factor which prevents the effective use of biological treatment method, since the biodegradation of oil products is highly dependent on the season of a year and takes place only during the warm period, when the microorganisms act as active decomposers. Biodegradation of oil and its products takes about 9 months in a temperate climate zone. By properly organizing the modern biological systems of treatment of soil polluted by oil products, considerably better result can be achieved compared to previously used methods. Soil heating is one of ways to increase the intensity of biodegradation process of oil products. For this purpose the solar energy, one of the alternative energy sources, was used. Changes of diesel fuel and heavy fuel oil concentrations in soil during cold and warm season were studied. In order to determine the heat transfer process in soil, the modeling of the part of defined solar system had been done. The modeling realized using FEM (Finite Element Method) computer software constituted on numerical solution of heat equation. Simulation results indicate the dependency of contaminated soil temperature from the outer air temperature as well as comparing the physical experiments with the modeling results. To summarize the results we can state, that the outcome of biological treatment of samples using solar-based heating system during cold and warm seasons was better in both cases of pollutants. Heat produced by solar collector intensified the process of degradation of pollutants: in samples with solar-based water heating system, the diesel fuel removal level reached 70 %, in case of heavy fuel oil -46 %, and in control samples it was 54 % for diesel fuel and 26% for heavy fuel oil. The treatment time of soil contaminated with oil products decreased accordingly. The obtained results allow to propose new technological principles of remediation of polluted soil, which decrease the treatment time, and thus the cost, and extends the area of application of alternative energy sources.
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